The present invention relates to a control device for an electric vehicle obtaining driving force from a traveling motor.
In recent years, a vehicle (EV) in which driving wheels are driven by a traveling motor or a hybrid vehicle in which driving force for the vehicle is obtained by a combination of a traveling motor and an engine has been developed and put into practical use. Not only a vehicle (HEV) in which a battery for supplying electric power to a traveling motor is charged by electric power generated by a generator driven by an engine, but also a vehicle (PHEV) in which a battery can be charged even by an external commercial use power supply have been developed and put into practical use as hybrid vehicles.
In the background art, a technique is available in which such an electric vehicle is made to travel in a limited traveling state in which the electric vehicle can travel with predetermined vehicle velocity or torque when there occurs an abnormality in an electrically driven system such as an abnormality in an electric equipment (a device such as a traveling motor or a battery, a control device, a communication device, etc.) or an abnormality in a communication system (for example, JP-A-2013-5590). The technique disclosed in JP-A-2013-5590 is a technique in which, when a drive instruction cannot be received from a control unit, torque limitation is reinforced stepwise to stop the vehicle. Thus, even if a drive instruction cannot be received from the control unit, it is possible to bring the vehicle into a safe state to avoid risk.
According to the technique disclosed in JP-A-2013-5590, since torque limitation is reinforced stepwise, the torque of the vehicle can be limited without giving an uncomfortable feeling to a driver. However, the torque limitation must be reinforced in a short time for some kind of abnormality or the like. In some traveling situation before the occurrence of the abnormality, reinforcement of torque limitation is not required for the traveling. In another case, no uncomfortable feeling is given to the driver even when torque is limited to a predetermined limited state. In other traveling conditions before the occurrence of the abnormality, an uncomfortable feeling may be given to the driver by torque limitation applied when a failure is detected.